In vehicles such as automobiles, there is a vehicle fitted with an under cover on a lower surface of the vehicle body in order to improve the aerodynamic characteristic of the vehicle. For example, the under cover includes a rectifying fin that protrudes downward under the floor of the vehicle body in order to stabilize the flow of air under the floor of the vehicle body. The rectifying fin has a blade thickness in the vehicle width direction, and is provided under the floor and formed to rise on a rear side of the rear wheels (refer to Patent Document 1).
Moreover, there is an under cover in which a rectifying protrusion that rectifies the air flow flowing on a rear surface of the under cover so as to flow at a lower position, is provided on the front side of a suspension component, under the floor in front of the rear wheels, in order to alleviate collision of the air flow flowing under the floor with the rear suspension component (refer to Patent Document 2).